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Old February 25th 08, 02:01 PM posted to uk.d-i-y
Rod Rod is offline
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First recorded activity by DIYBanter: Jul 2006
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Default Is undercoat / sealer necessary for new plaster?

diy-newby wrote:
"somebody" wrote in message
In message , Steven Campbell
After having some plaster work done I thought there would nothing else to
but give the walls a few coats of white emulsion. However after the 3rd
coat, I can still see a difference of colour from the old plaster to the

I've still to do a couple of walls where there is old and new plaster on
same wall.

Is it worth putting undercoat on first? Would it make a big difference?

Also would it be worth while applying the undercoat to the walls I have
previously painted that the new plaster can still be seen?


You should apply a "****" coat first. So called because the paint has been
watered down so much it is as thin as ****.

Basically, first coat, any cheap old emulsion mixed approx 50/50 with

I've had luck with some rooms where one **** coat and one proper coat was
all that was needed, others needed a **** coat and two proper coats. (all
these rooms done by the same plasterer).

One thing I've never got away with though is plaster coving. Always seems
to need a gazillion coats regardless.


Think I heard mention a while ago about sealing the plaster first with a
50 - 50 mix of PVA and white emulsion.

There have indeed been mentions of using PVA (in various dilutions,
etc.) on new plaster. Many of them also ask why the emulsion coats are
peeling off...

As already said - ****-coat following by decent quality coat(s).